The field of this invention is analyte determination, particularly blood analyte determination and more particularly blood glucose determination.
Analyte concentration determination in physiological samples is of ever increasing importance to today""s society. Such assays find use in a variety of application settings, including clinical laboratory testing, home testing, etc., where the results of such testing play a prominent role in the diagnosis and management of a variety of disease conditions. Analytes of interest include glucose for diabetes management, cholesterol for monitoring cardiovascular conditions, and the like. In response to this growing importance of analyte concentration characterization, a variety of analyte concentration characterization protocols and devices for both clinical and home testing have been developed.
One type of device that is employed for analyte concentration determination is a test strip. Oftentimes, such a test strip is based on the production of hydrogen peroxide and the subsequent detection thereof. Analyte concentrations that may be determined using such assays include: cholesterol, triglycerides, glucose, ethanol and lactic acid. For example, glucose is quantitated using such assays by first oxidizing glucose with glucose oxidase to produce gluconic acid and hydrogen peroxide in a reaction area or zone of the test strip. The resultant hydrogen peroxide, in conjunction with a peroxidase, causes the conversion of one or more organic substrates, i.e., an indicator, into a chromogenic product, which product is then detected and related to the glucose concentration in the initial sample.
Oftentimes, a test strip for determining analyte concentration may be configured to include more than one reaction areas or zones, where the reaction areas include the one or more testing or reaction reagents necessary for analyte determination. Thus, it will be apparent that in the above described multi reaction area test strips it is important to segregate the reaction areas from each other so as not to contaminate the separate areas, for example with reagents or even final product from other reaction areas. This is particularly important if the reaction areas have different reagents or different concentrations of the same reagents. However, even if all of the reaction areas were to have the same reagents present in the same concentrations, it is obvious that reaction area isolation is necessary to prevent cross contamination and provide accurate, reliable and reproducible analyte determination results.
One method that has been proposed to isolate reaction areas of a multi reaction area test strip is disclosed in U.S. Pat. No. 5,843,691 to Douglas, et. al. The ""691 patent teaches the creation of both non-bibulous (non absorbent) and bibulous (absorbent) areas on a test strip membrane by crushing the membrane to make it non bibulous (but still hydrophilic) everywhere except for the reaction areas, which remain bibulous. This test strip includes an intermediate layer which lies adjacent the membrane having cut outs to provide physical barriers around each reaction area. The intermediate layer barriers are needed to prevent sample located in one reaction area from moving to other reaction areas over the non-bibulous, but hydrophilic areas, thereby contaminating the other reaction areas. As such, the intermediate layer must be precisely aligned with each reaction area so as to prevent such contamination and allow the required amount of sample to be applied to each reaction area. However, this method of compressing the membrane to create a plurality of bibulous reaction areas amongst a non bibulous background and separating the reaction areas, while effective, can be complex and costly to manufacture due to its compression step and the necessity of precisely aligning the intermediate layer with the reaction areas of the test strip.
Due to the broad applicability of analyte determination protocols, there continues to be interest in the identification of new devices and methods in this area. Of particular interest would be the development of such devices and methods of use thereof which are simple to use, accurate, precise and easy and low cost to manufacture.
Test strips and methods for their manufacture and use in the determination of the concentration of at least one analyte in a physiological sample are provided. The subject test strips have a plurality of reaction zones defined by a hydrophobic barrier. The reagent compositions present in each reaction zone may be the same or different. In addition, each reaction zone may have a separate fluid channel, or two or more of the reaction zones may have separate channels that merge into a single channel. In use, sample is applied to a subject test strip, a signal is detected and then related to the amount of analyte in the sample. Also provided are methods for manufacturing the subject test strips using thermal transfer technology to apply the hydrophobic barrier. Finally, kits are provided for use in practicing the subject methods.